GJB2 and Palmoplantar keratoderma: Ten of the 11 subjects had additional PPK-associated epidermal abnormalities in their hands and feet, including thickening and peeling of the skin, keratoderma, erythema, callus, deep fissures, brittle, thickened or spoon nails, knuckle pads and circular keratotic constriction bands (Figure 1).